1. A) Field of the Invention
The present invention relates to a solid state image pickup device and an endoscope using a solid state image pickup device.
1. B) Description of the Related Art
Various structures and manufacture methods are known for a solid state image pickup device (semiconductor chip) whose light reception region is protected with a protective glass (e.g., refer to Japanese Patent Laid-open Publication No. 2004-6834).
FIGS. 7A to 7G are schematic cross sectional views illustrating a solid state image pickup device using a wafer level chip size packaging (CSP) process.
Reference is made to FIG. 7A. A protective glass 57 and a silicon substrate 55a are bonded together with adhesive 56 of, for example, an ultraviolet ray curing type. Spacers are formed by using the silicon substrate 55a in the next process.
Reference is made to FIG. 7B. Resist patterns are formed on the silicon substrate 55a by photolithography in the areas where spacers are to be formed. The silicon substrate 55a is then etched to form spacers 55.
Reference is made to FIG. 7C. The regions between spacers 55 excepting the regions between devices are filled with resist 58, and the protective glass 57 is etched to a predetermined depth.
Reference is made to FIG. 7D. The etched region of the protective glass 57 constitutes an inter-device groove 60. Adhesive 54 of, for example, a thermosetting type is coated on the bottoms of the spacers 55. With the processes shown in FIGS. 7A to 7D, a sealing cover glass is formed.
Reference is made to FIG. 7E. Next, a solid state image pickup device substrate is formed.
First, a cut groove 69 is formed in the surface layer of the silicon substrate 51 by etching or the like, in the area corresponding to a dicing line for separating the substrate into each semiconductor chip. Next, a solid state image pickup device 68 is formed by ordinary silicon processes. A wiring layer is formed on the substrate surface, and pads 59 of metal material for external connection are formed.
Reference is made to FIG. 7F. Position alignment is performed and the sealing cover glass is placed on the solid state image pickup device substrate. The sealing glass cover and substrate are integrally bonded with heated adhesive 54. This process is preferably executed in a vacuum state, a nitrogen gas atmosphere or an inert gas atmosphere, or in an atmosphere of nitrogen gas or inert gas mixed with some air.
Reference is made to FIG. 7G. The upper side of the protective glass 57 is removed down to the inter-device groove 60 by chemical mechanical polishing (CMP). The bottom side of the silicon substrate is removed up to the cut groove 69 by CMP to separate the substrate into each semiconductor chip.